Methods of fabricating a semiconductor device

Abstract

Methods of fabricating a semiconductor device are provided. Methods of forming a finer pattern of a semiconductor device using a buffer layer for retarding, or preventing, bridge formation between patterns in the formation of a finer pattern below resolution limits of a photolithography process by double patterning are also provided. A first hard mask layer and/or a second hard mask layer may be formed on a layer of a substrate to be etched. A first etch mask pattern of a first pitch may be formed on the second hard mask layer. After a buffer layer is formed on the overall surface of the substrate, a second etch mask pattern of a second pitch may be formed thereon in a region between the first etch mask pattern. The buffer layer may be anisotropically etched using the second etch mask pattern as an etch mask, forming a buffer layer pattern. The second hard mask layer may be anisotropically etched using the first etch mask pattern and/or the buffer layer pattern as etch masks, forming a second hard mask pattern. The first hard mask layer may be anisotropically etched using the second hard mask pattern as an etch mask, forming a first hard mask pattern. The etched layer may be anisotropically etched using the first hard mask pattern as an etch mask.

1. A method of fabricating a semiconductor device comprising:
 depositing a base layer on a substrate; 
 forming a first hard mask layer on the base layer; 
 forming a second hard mask layer on the first hard mask layer; 
 forming a first etch mask pattern on the second hard mask layer wherein the first etch mask pattern is repeatedly formed having a first pitch; 
 forming a buffer layer on a surface of a resultant structure having the first etch mask pattern; 
 forming a second etch mask pattern on the buffer layer using a photolithography process, wherein the second etch mask pattern is repeatedly formed having the first pitch between the first etch mask pattern; 
 etching the buffer layer using the second etch mask pattern as an etch mask, forming a buffer layer pattern; 
 etching the second hard mask layer using the first etch mask pattern and the buffer layer pattern as etch masks, forming a second hard mask pattern having a second pitch wherein the second pitch is a half of the first pitch; 
 etching the first hard mask layer using the second hard mask pattern as an etch mask, forming a first hard mask pattern which is repeatedly formed having the second pitch; and 
 etching the base layer using the first hard mask pattern as an etch mask, forming a pattern which is repeatedly formed having the second pitch. 
 
     
     
       2. The method according to  claim 1 , wherein the first hard mask layer is formed of an amorphous carbon layer (ACL). 
     
     
       3. The method according to  claim 1 , wherein forming the first etch mask pattern includes forming a single layer of a material selected from the group consisting of an oxide layer, a nitride layer, an oxynitride layer and a polysilicon layer or a composite layer thereof. 
     
     
       4. The method according to  claim 1 ,
 wherein forming the first etch mask pattern includes forming a third hard mask layer on the second hard mask layer; forming a first photoresist pattern having the first pitch on the third hard mask layer; and etching the third hard mask layer using the first photoresist pattern as an etch mask, forming a third hard mask pattern. 
 
     
     
       5. The method according to  claim 4 , wherein forming the second hard mask layer includes using a material having different etch characteristics than etch characteristics of the first hard mask layer; and forming a single layer of a material selected from the group consisting of an oxide layer, a nitride layer, an oxynitride layer and a polysilicon layer or a composite layer thereof. 
     
     
       6. The method according to  claim 4 , wherein forming the third hard mask layer includes using a material having different etch characteristics than etch characteristics of the second hard mask layer; and
 forming a single layer, wherein the material is selected from the group consisting of an oxide layer, a nitride layer, an oxynitride layer and a polysilicon layer or a composite layer thereof. 
 
     
     
       7. The method according to  claim 1 ,
 wherein forming the first etch mask pattern includes forming a first photoresist pattern having the first pitch on the second hard mask layer; and etching a portion of the second hard mask layer to a desired thickness from a total thickness of the second hard mask layer, using the first photoresist pattern as an etch mask, forming a protrusion portion under the first photoresist pattern. 
 
     
     
       8. The method according to  claim 7 , wherein forming the second hard mask layer includes using a material having different etch characteristics than etch characteristics of the first hard mask layer; and forming a single layer of a material selected from the group consisting of an oxide layer, a nitride layer, an oxynitride layer and a polysilicon layer or a composite layer thereof. 
     
     
       9. The method according to  claim 1 , further comprising:
 forming a capping layer on the surface of the resultant structure having the first etch mask pattern prior to forming the buffer layer. 
 
     
     
       10. The method according to  claim 9 , wherein forming the second hard mask layer includes using a material having different etch characteristics than etch characteristics of the first hard mask layer; and forming a single layer of a material selected from the group consisting of an oxide layer, a nitride layer, an oxynitride layer and a polysilicon layer or a composite layer thereof. 
     
     
       11. The method according to  claim 9 , wherein forming the capping layer includes using at least one material selected from the group of an ACL, an organic anti-reflective coating (ARC) layer, lower viscosity polymer, an oxide layer and an oxynitride layer. 
     
     
       12. The method according to  claim 9 , wherein the capping layer is formed with a thickness of about 50 Å-1000 Å. 
     
     
       13. The method according to  claim 9 , wherein forming the capping layer includes forming a capping material layer on the surface of the resultant structure having the first etch mask pattern; and performing multi-steps of thermal treatment on the capping material layer. 
     
     
       14. The method according to  claim 13 , wherein the multi-steps of thermal treatment includes sequentially performing a soft bake process of thermally processing at a first temperature and a hard bake process of thermally processing at a second temperature higher than the first temperature. 
     
     
       15. The method according to  claim 1 , wherein forming the buffer layer includes using a bottom resist material in a bi-layer resist (BLR) process, and forming the second etch mask pattern includes using a photoresist pattern containing silicon (Si). 
     
     
       16. The method according to  claim 15 , wherein forming the buffer layer includes coating the surface of the resultant structure having the first etch mask pattern with the bottom resist material; and baking the bottom resist material by a hard bake process. 
     
     
       17. The method according to  claim 1 , further comprising:
 forming a fourth hard mask layer on the buffer layer, prior to forming the second etch mask pattern; and 
 etching the fourth hard mask layer using the second etch mask pattern as an etch mask, forming a fourth hard mask pattern. 
 
     
     
       18. The method according to  claim 17 , wherein forming the buffer layer includes using an amorphous carbon layer (ACL) or a bottom resist material; and forming the fourth hard mask layer includes using a material having different etch characteristics than etch characteristics of the buffer layer material. 
     
     
       19. The method according to  claim 17 , wherein forming the fourth hard mask layer includes using a single layer wherein the material is selected from the group consisting of an oxide layer, a nitride layer, an oxynitride layer and a polysilicon layer or a composite layer thereof. 
     
     
       20. The method according to  claim 1 , wherein forming the buffer layer includes covering any height differences on the substrate; and forming a flat upper surface. 
     
     
       21. The method according to  claim 1 , wherein forming the buffer layer includes depositing a buffer material on the surface of the resultant structure having the first etch mask pattern; and polishing the deposited buffer material such that an upper surface thereof is planarized. 
     
     
       22. The method according to  claim 1 , further comprising:
 forming an organic anti-reflective coating (ARC) layer on the surface of the resultant structure having the first etch mask pattern, prior to forming the buffer layer. 
 
     
     
       23. The method according to  claim 1 , forming the second etch mask pattern includes forming a third hard mask layer on the buffer layer; forming a second photoresist pattern having the first pitch on the third hard mask layer; and etching the third hard mask layer using the second photoresist pattern as an etch mask, forming a third hard mask pattern.